Mercurial > lasercutter

     1 /**

     2  *   Copyright (c) Rich Hickey. All rights reserved.

     3  *   The use and distribution terms for this software are covered by the

     4  *   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)

     5  *   which can be found in the file epl-v10.html at the root of this distribution.

     6  *   By using this software in any fashion, you are agreeing to be bound by

     7  * 	 the terms of this license.

     8  *   You must not remove this notice, or any other, from this software.

     9  **/

    10 

    11 /* rich Jun 28, 2007 */

    12 

    13 package clojure.lang;

    14 

    15 public class Delay implements IDeref{

    16 Object val;

    17 IFn fn;

    18 

    19 public Delay(IFn fn){

    20 	this.fn = fn;

    21 	this.val = null;

    22 }

    23 

    24 static public Object force(Object x) throws Exception{

    25 	return (x instanceof Delay) ?

    26 	       ((Delay) x).deref()

    27 	       : x;

    28 }

    29 

    30 synchronized public Object deref() throws Exception{

    31 	if(fn != null)

    32 		{

    33 		val = fn.invoke();

    34 		fn = null;

    35 		}

    36 	return val;

    37 }

    38 }
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
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